The objectives are to study the development of sustained attention in young infants and to relate development in sustained attention to concurrent heart rate (HR) changes. The specific aims are: 1) To study sustained, subject-controlled attention in infants from 8 to 26 weeks of age, and to study the control of saccadic eye movements during heart-rate-defined attention phases, in order to infer the neurodevelopmental systems controlling attention-directed eye movements; 2) To study the cortical basis of planned eye movements in young infants with high-density EEG and ERP, and to study the effect of attention on infant saccade planning; 3) To study the development of attention in infants and young preschool children during extended television viewing and to further extend the study of sustained attention. This research examines the patterns of attention found in normal children, relating those attention patterns to physiological processes (HR. EEG), and may provide a "model preparation" for the study of children with irregular patterns of attention. Experiment 1 will examine the characteristics of the "main sequence" in eye movements in the early parts of this age range (8, 11, 14, 17, 20, 23, 26 weeks) and will examine the effect of attention on the main sequence. Experiments 2 and 3 will examine infant planned eye movements under the influence of HR-defined attention phases. Experiment 2 will examine covert shifts of attention to peripheral stimuli in infants at 8, 14, and 20 weeks of age. This study will use "high-density" EEG recording to infer cortical sources of attention-directed eye movement control. Experiment 3 will use the "visual expectation procedure" to induce anticipatory eye movements in young infants (8, 14, 20 weeks) while recording high-density EEG to examine the role of the cortex in infant planned saccades. Experiment 4 will extend the study of HR-defined attention phases to extended television viewing in older infants and the early preschool years (6 months to 2 years). It is predicted that 1) age changes in sustained attention will interact with development changes in eye movements to affect attention-directed eye movements; 2) emerging technologies for inferring cortical activity using high-density EEG recording should reveal the cortical sources involved in the control of infant planned saccades; 3) sustained attention will be closely related to patterns of extended television viewing in the early preschool years (up to age 2 years).